An existing communications system, for example, a global system for mobile communications (GSM) system, a universal mobile telecommunications system (UMTS), or a Long Term Evolution (LTE) system, usually works in a carrier frequency band below 3 GHz. As intelligent terminals especially video services emerge, a high frequency band, for example, 3 GHz to 250 GHz, is becoming a candidate frequency band for a next-generation communications system.
A large-scale loss usually increases with an increase in a carrier frequency. For example, a path loss of 70 GHz is greater than a path loss of 28 GHz. In addition, factors such as the atmosphere and vegetation all cause a larger-scale loss on a high-frequency carrier. Therefore, channel receiving quality decreases with an increase in a carrier frequency. For a service channel, an increase in a large-scale loss and a decrease in channel receiving quality that are caused by an increase in a carrier frequency may be compensated by using a beamforming technology and a retransmission combining technology, thereby ensuring quality of high-frequency channel transmission. A common channel or signal usually includes control information. For transmission of the common channel or signal, for example, transmission of a broadcast channel, a synchronous signal, or a control channel, a large-scale loss cannot be compensated by using an antenna gain brought by the beamforming technology, because the common channel or signal usually carries some cell public information or signals, and coverage of all user equipment's in an entire cell needs to be ensured so that the user equipment's can receive the common channel or signal. Therefore, a beam used for transmission of the common channel or signal cannot be excessively narrow, and a relatively large antenna gain similar to that of the service channel cannot be obtained. In addition, reliability of the transmission of the common channel/signal cannot be enhanced by using the retransmission combining technology. Therefore, quality and reliability of transmission of a common channel or signal on a high-frequency carrier are relatively poor.